Polypropylene in general is produced in a process using multiple gas and/or liquid phase reactors. For a polypropylene impact copolymer, a propylene homopolymer is normally produced in a first stage polymerization, followed by ethylene-propylene or other alpha olefin-propylene copolymer in a second stage polymerization. The overall properties of the impact copolymer are a function of the homopolymer produced in the first stage and the copolymer produced in the second stage. Further, the qualities of the homopolymer and copolymer are a function of the polymerization conditions in the first and second stage respectively. As a result, manufacturers are constantly looking for new ways to manipulate polymerization conditions to produce improved impact copolymers. In addition, producing more polymers for a given amounts of catalyst and co-catalyst employed for the polymerization would be beneficial.
It would be desirable to provide a new method for manipulating the properties as well as the amounts of polymers produced in the second stage polymerization.